Vehicle engine brake control apparatus

Abstract

An engine ECU and a brake ECU of a vehicle control apparatus performs any one of a mechanical brake which converts a kinetic energy using rotation of a driving wheel rotation into thermal energy using friction and a regeneration brake which converts the kinetic energy of the driving wheel rotation into electric energy using regeneration, during a vehicle deceleration, after an engine brake changes a deceleration ratio which is a rotation number ratio of driving wheels with respect to the rotation number of an engine.

The invention claimed is: 
     
       1. A vehicle control apparatus comprising:
 a driver support system ECU including an application program which supports a driver's driving operation, and outputting a required driving force corresponding to a deceleration degree required by the application program and an allowable upper limit rotation number in the rotation number of the driving source, 
 an engine ECU performing an engine brake changing a deceleration ratio, which is a rotation number ratio of driving wheels with respect to the rotation of a driving source according to the required driving force and the upper limit rotation number output by the driver support system ECU, 
 a brake ECU performing any one of a mechanical brake, which converts a kinetic energy of a driving wheel rotation into a thermal energy using friction, and a regeneration brake, which converts the kinetic energy of the driving wheel rotation into an electric energy using regeneration, during a vehicle deceleration of a vehicle, in conjunction with the engine brake, 
 wherein the engine ECU can change the deceleration ratio with a continuously variable stage, and assumes that characteristics of the rotation number of the driving source with respect to a deceleration degree are linear shape, and determines the deceleration ratio from a target rotation number of the driving source, and performs the engine brake according to the required driving force output by the driver support system ECU by a target rotation number equal to or lower than the upper limit rotation number, 
 wherein the brake ECU, compensates for an insufficient deceleration degree by performing at least one of the mechanical brake and the regeneration brake in conjunction with the engine brake, when the deceleration degree by the engine brake is insufficient compared to the deceleration degree according to the required driving force, and 
 wherein the brake ECU during the engine brake, continues the engine brake without performing the mechanical brake and the regeneration brake, after the rotation number of the driving source reaches the upper limit rotation number, and thereafter performs any one of the mechanical brake and the regeneration brake. 
 
     
     
       2. The vehicle control apparatus of  claim 1 ,
 wherein the engine ECU maintains the deceleration ratio while continuing the engine brake, during the engine brake, after the rotation number of the driving source reaches the upper limit rotation number. 
 
     
     
       3. The vehicle control apparatus according to  claim 1 ,
 wherein the brake ECU and the brake ECU control the deceleration degree so that variations in a rate change of the deceleration degree are within a predetermined value.